Meet Rotundo:
He received the bulk of the family genes.
And Sticko:
He's the middle child and he got squished.
And Doc:
Who inexplicably was born with the eleventh Doctor Who's legs.
You can see the family resemblance can't you. They all look very much the same... and yet they look slightly different.... Maybe it would help if we stuck them all in a row:
An artist will often use the same colors to make objects that are very different. So, how did I make these three characters look different?
Well, it's not in the face, even though each face has a different expression.
I made them look different through the body proportions. Papa-o has the most normal proportions. I made Rotundo wider, even making his legs and arms wider. Sticko is thinner, and if you look real closely, you'll notice that his legs are even thinner. The Doc is much taller with legs of normal proportions under a hobbit body.
Notice further... where did I put the stomach of each character in his body? And how big is that stomach? Where did I put his knees? How much space did I put between each characters legs? How wide did I make each leg, and does it stay that wide?
God made each of us with the same basic body shape. He put two eyes, a nose, and a mouth on our faces, and they appear in about the same places. But you look like you and I look like me. Why is that? Well, God made my nose slightly larger than your nose and he put it in a slightly different spot between the eyebrows and the mouth. And he tweaked your face too. That's proportions.
So, what should an artist do with all these people running around who are all just slightly different? First, he should know the pattern—the basic human proportions. Second, he should practice drawing specific people, noticing how they are different than the general pattern. Third, he should talk with other artists about what he's seeing and share his work with other artists, just so that he can remain objective. Otherwise, he could be making hobbits when he thinks he's making humans....